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Pennsylvania inland flooding risk

67 counties scored 2 rated Very High

Philadelphia County has the highest inland flooding risk in Pennsylvania, scoring 99.6 out of 100 — rated "Very High" by FEMA's National Risk Index. NOAA has recorded 2,690 inland flooding events across Pennsylvania over the past decade.

# County NRI score Rating NOAA events
2016–2026
1 Philadelphia County 99.6 Very High 101
2 Allegheny County 99.2 Very High 328
3 Montgomery County 98.2 Relatively High 120
4 Bucks County 97.1 Relatively High 72
5 Lancaster County 96.9 Relatively High 64
6 Lehigh County 95.4 Relatively High 51
7 Luzerne County 95.3 Relatively High 63
8 Berks County 94.8 Relatively High 129
9 Dauphin County 94.8 Relatively High 14
10 Delaware County 94.4 Relatively High 113
11 Chester County 94.3 Relatively High 164
12 Lackawanna County 94.1 Relatively High 57
13 Westmoreland County 93.8 Relatively High 173
14 Northampton County 93.6 Relatively High 52
15 York County 93.3 Relatively High 40
16 Washington County 91.4 Relatively Moderate 113
17 Cumberland County 91.1 Relatively Moderate 6
18 Schuylkill County 90.8 Relatively Moderate 15
19 Erie County 90.7 Relatively Moderate 11
20 Fayette County 90.6 Relatively Moderate 61
21 Butler County 89 Relatively Moderate 53
22 Lycoming County 89 Relatively Moderate 26
23 Northumberland County 88.3 Relatively Moderate 8
24 Monroe County 88.1 Relatively Moderate 23
25 Mercer County 87.9 Relatively Moderate 37
26 Blair County 87.5 Relatively Moderate 17
27 Crawford County 87.2 Relatively Moderate 9
28 Beaver County 87 Relatively Moderate 59
29 Bradford County 86.1 Relatively Moderate 113
30 Cambria County 85.7 Relatively Moderate 12
31 Armstrong County 85.1 Relatively Moderate 37
32 Lebanon County 84.9 Relatively Moderate 15
33 Franklin County 84.3 Relatively Moderate 7
34 Bedford County 84 Relatively Moderate 12
35 Mifflin County 83.6 Relatively Moderate 1
36 Lawrence County 83.1 Relatively Moderate 66
37 Warren County 82.8 Relatively Moderate 3
38 Centre County 81.2 Relatively Moderate 8
39 Clearfield County 80.6 Relatively Moderate 14
40 Somerset County 80 Relatively Moderate 38
41 Tioga County 78.9 Relatively Moderate 16
42 Pike County 78.8 Relatively Moderate 5
43 Columbia County 78.6 Relatively Moderate 8
44 Indiana County 77.8 Relatively Moderate 39
45 Adams County 76.2 Relatively Moderate 6
46 Jefferson County 74.5 Relatively Moderate 37
47 Greene County 74.3 Relatively Moderate 38
48 Venango County 74.1 Relatively Moderate 35
49 McKean County 73.2 Relatively Moderate 4
50 Union County 71.8 Relatively Low 6
51 Clinton County 71.3 Relatively Low 4
52 Wayne County 71.3 Relatively Low 28
53 Snyder County 71.2 Relatively Low 1
54 Susquehanna County 71 Relatively Low 60
55 Perry County 69.5 Relatively Low 2
56 Wyoming County 69.2 Relatively Low 21
57 Huntingdon County 68.8 Relatively Low 5
58 Elk County 68 Relatively Low 0
59 Carbon County 67.5 Relatively Low 2
60 Juniata County 60.3 Relatively Low 3
61 Potter County 55.2 Relatively Low 10
62 Clarion County 52.2 Relatively Low 33
63 Forest County 43.5 Relatively Low 1
64 Cameron County 40.7 Relatively Low 0
65 Montour County 38.3 Relatively Low 2
66 Sullivan County 37.4 Relatively Low 14
67 Fulton County 21.5 Very Low 13

Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.

Inland Flooding risk nationally:

Top 50 US counties

Other hazard risks in Pennsylvania:

WildfireCoastal FloodingEarthquakeHeat WaveTornadoHurricaneHailStrong WindWinter WeatherIce StormCold WaveLightningDroughtLandslideAvalancheTsunamiVolcanic Activity

Frequently asked questions

What is the highest inland flooding risk county in Pennsylvania?

Philadelphia County, PA has the highest inland flooding risk in Pennsylvania, with a FEMA National Risk Index score of 99.6 out of 100 (rated "Very High").

How many counties in Pennsylvania are rated Very High for inland flooding risk?

2 of 67 scored Pennsylvania counties are rated "Very High" for inland flooding risk by FEMA's National Risk Index.

What causes inland flooding risk in Pennsylvania?

Inland flooding covers riverine and surface (pluvial) flooding — the most common and costly natural disaster type in the US. High scores appear across river floodplains in the Midwest, South, and Mid-Atlantic, where legacy development in flood-prone areas and aging stormwater infrastructure concentrate risk.